Let A = union ( i from 1 to infinity) of M_i, Mi's are disjoint, show that m*(A) = sum (i from 1 to infinity) of |M_i|
m*(A) is the outer measure of A, that is, m*(A) = inf sum (i from 1 to infinity) of M_i.
PLEASE NOTICE THE = SIGN, A = the union, not a subset of the union.
Outer measures are investigated. The solution is detailed and well presented.